A friend and I were recently taking a stroll down memory lane—remembering elementary school in our respective cities in the Midwest (USA). We were comparing notes on having to read aloud to our classmates—remember that? It was a small group activity, and embarrassing when you came across a word you’d not read or pronounced before. I found myself wondering what the goal of the reading aloud exercise was.
Shortly after that conversation, Stanislas Dehaene’s research on “How learning to read changes the cortical networks for vision and language” appeared on the Science magazine’s online ScienceNow. It was time to learn what goes on “upstairs” as we learn to read.
The authors pointed to previous research showing that “acquisition of reading, a major event in children’s lives, is now recognized as capable of changing both brain anatomy and brain activation.“ In terms of hearing, reading leads to “phonemic awareness” (the answer to my question: reading aloud allows one to gain an understanding of what letter combinations, words, sound like. It combines viewing words with learning how they sound). Furthermore, in studies of both normal and dyslexic children, reading has been shown to activate a specific brain site in left, occipito-temporal cortex, a location referred to as “visual word form area, VWFA”.
The authors note that reading is a “cultural invention”, that in evolutionary terms it is an event too new to involve dedicated genetic or developmental mechanisms. As such, they asked if learning to read invaded and recycled cortical space devoted to evolutionarily older functions. Other research groups previously showed that expertise for non-face stimuli causes a reduction in face responses. Dehaene et al. asked whether reading, which uses an identical site in the brain of all cultures, could require a reorganization of nearby responses to static objects (houses, faces, etc.).
fMRI Studies on Three Subject Types
To address these questions, the researchers used functional magnetic resonance imaging (fMRI—check this link for a nice description of how fMRI works) to perform brain scans on a variety of subjects. Because fMRI work frequently is done on educated college students, Dehaene’s team studied a variety of subjects from varying educational and socio-economic backgrounds. This research was conducted on 63 Portuguese and Brazilian subjects that fit into three different education/experience groups: 32 unschooled adults (10 of these were illiterate and 22 called ex-iliterates with variable reading skills) and 31 schooled, literate adults (including 11 literate subjects matched to the illiterates in socio-economic status).
Reading skills in these groups were verified using tasks such as letter identification, word and fake word, as well as sentence reading.
The authors studied which regions of the brain were affected by reading performance of simple sentences. A large effect was noted in the VWFA and at a right occipital site, as shown by fMRI. These regions were shown to be strictly visual, by their lack of activation to spoken sentences. From their comparisons the authors concluded that with literacy, written materials activate right occipital cortex, induce strong activation in the left ventral visual cortex (classical VWFA) and resulted in access to the frontal language areas.
The researchers found evidence of competition with other visual categories in the occipito-temporal cortex. At the primary VWFA location, in separate study runs, the subjects showed equally strong responses to both word strings and other visual stimuli, such as faces and tools. They then tested for predicted cortical competition by looking for a reduced response to visual stimuli with increased reading performance—as seen in more literate subjects. At peak VWFA stimuli, response to other visual challenges diminished slightly, across all groups.
The authors concluded that whether literacy was gained during childhood years or later in adulthood, it enhanced brain responses by boosting organization of the visual cortices, causing an enhanced response at the VWFA region. Literacy allowed virtually all of the left hemisphere spoken word network to be activated by written sentences. The authors felt that this pointed to reading, a relatively recent cultural invention, achieving the efficiency of spoken language, one of our most advanced and longest established channels of communication. Thirdly, they report that literacy enhances spoken language processing.
This report and the fMRI scan results shown herein have given me a new appreciation of the efforts young children undergo as they learn letters and begin to read. They are literally having a mind changing experience, undergoing structural brain changes, and tapping into ancient, as well as newer cortical circuitry. We’ve all seen children that excel at reading, as well as those for whom it’s not so easy. This report is instructive in several ways, not the least of how strongly reading affects cortical development.
Dehaene S, Pegado F, Braga LW, Ventura P, Filho GN, Jobert A, Dehaene-Lambertz G, Kolinsky R, Morais J, & Cohen L (2010). How Learning to Read Changes the Cortical Networks for Vision and Language. Science (New York, N.Y.) PMID: 21071632
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